I have installed a couple of 700 switches initially to test things out, and upon looking to get more switches I noticed they now have the 800 LR ones.
I live in a 3-story townhome and I EXPECT my mesh network/repeating to be adequate.. but is there realistically any reason to choose the newer 800 over the 700 if the 700 can be had cheaper? At a glance they LOOK identical. Would they actually respond any faster or anything like that?
Also, as of RIGHT NOW I am using Hubitat C7 which I don't even think is an 800 series chip?
The 800 chip promises to be less buggy than the 700 (which is not made any more), so "may" be better overall. That said for your described uses, I wouldn't expect any difference in practical usage.
Mains powered devices: For same price I would go 800. If cheaper, and no desire to ever use LR on the device, I would go 700.
Battery powered devices: I would go 800 if there were a choice, as 800 is lower power which should equal longer battery life.
